Biochemistry - Structure and Properties of Amino Acids - Discussion

Cystein is hydrophilic, it can lose the proton in the side chain and become neg charged at higher pH.

The correct answer is B) SF is hydrophilic.

Cysteine is a polar uncharged amino acid so, its a hydrophobic and due to the sulphur it is highly reactive and can form cystine.

I think B too because C has that sulfhydryl group which can form H bonds.

You can correct me if am wrong.

The sulphur containing amino acids (cysteine and methionine) are generally considered to be nonpolar and hydrophobic.

Yea this is definitely wrong. Cysteine side chain is sulfhydryl which is extremely electronegative causing the molecule to be very polar and thus very hydrophilic. The answer is B.

The correct answer will be B that because the following charged:

Arginine - Arg - R.
Lysine - Lys - K.
Aspartic acid - Asp - D.
Glutamic acid - Glu - E.

Polar (may participate in hydrogen bonds)hydophilic:

Glutamine - Gln - Q.
Asparagine - Asn - N.
Histidine - His - H.
Serine - Ser - S.
Threonine - Thr - T.
Tyrosine - Tyr - Y.
Cysteine - Cys - C.
Methionine - Met - M.
Tryptophan - Trp - W.

Hydrophobic (normally buried inside the protein core):

Alanine - Ala - A.
Isoleucine - Ile - I.
Leucine - Leu - L.
Phenylalanine - Phe - F.
Valine - Val - V.
Proline - Pro - P.
Glycine - Gly - G.

I think B is correct because the side chain is polar.

@Jordan, you are wrong, lecture notes say hydrophobic. Get it right.

I think the correct answer is B not C because the side chain of cysteine is hydrophillc not hydrophobic.